At present, a driving unit of a liquid crystal display device is generally integrated on a base substrate of an array substrate. For example, a driving circuit such as a gate driving circuit is generally integrated on an outer side of a display region of an array substrate, and the gate driving circuit carries out driving thin film transistors in the display region by receiving and transmitting a voltage signal.
However, since signal lines between the driving circuit and the thin film transistors are made of indium tin oxide, etching with hydrochloric acid is usually adopted for patterning in a manufacturing process, which will result in residual chlorine ions Cl−.
In addition, moisture may permeate to a display device during use, which introduces oxygen ions O2−. Therefore, a phenomenon that trivalent indium is reduced to elemental indium happens on the signal line of the driving circuit to which a relatively low voltage is applied (a cathode) during a driving process, that is, the following electrochemical reactions (electrolytic cell effect) occur on the signal line of the driving circuit.
Cathodic reaction: In3++3e−=In.
Anodic reaction: 2Cl−−2e−=Cl2, or 2O2−−4e−=O2.
The aforesaid phenomenon increases resistance of the signal line of the driving circuit, which has an effect on the driving of the thin film transistors, thereby causing abnormal display.